1. Technical Field
The present invention relates to a clamp mechanism to support information mediums such as CDs (Compact Discs) and DVD (Digital Versatile Discs) on a turntable and to an information replay apparatus equipped with the clamp mechanism.
2. Related Art
An information replay apparatus that requires a compact disc serving as an information-recording medium has usually a clamp mechanism for supporting the compact disc on a turntable.
A conventional clamp mechanism is disclosed by Japanese Patent Publication (Laid-open) No. 10-162463, of which longitudinally sectioned configurations are shown in FIGS. 9 and 10. FIG. 9 represents an unclamping state of the clamp mechanism, while FIG. 10 represents a clamping state thereof.
As shown in FIGS. 9 and 10, a chuck rotating mechanism (that is, a clamp mechanism) 1 has a disc table 2 (that is, a turntable). The disc table 2 is fitly mounted on a rotation shaft 3a and a rotation motor 3, so that the disc table 2 is driven by the rotation axis 3a. A chuck-moving member 4 is fitly mounted on a cylindrical body of the disc table 2 and slidable along the cylindrical body surface in the up-and-down direction. Between the chuck-moving member and a body of the rotation motor 3, a spring is inserted to force the chuck-moving member 4 upward. Both of the chuck-moving member 4 and the spring 5 can be driven together with the disc table 2 in response to rotation of the rotation motor 3. As shown, the chuck-moving member has a tapered flange located around its main body and of which upper surface is descendent outwardly. When an operating piece 6, which is part of a chuck control mechanism, is moved to the left in FIGS. 9 and 10, the chuck-moving member 4 is forcibly lowered against a pushing force of the spring 5.
In addition, the chuck rotating mechanism 1 has three chuck claws 7, and each of the side views of each claw is formed into an almost V-shape. Each chuck claw 7 has a rotation shaft 7a not only formed at its base but also rotatable around an axis in the horizontal direction. The disc table 2 supports the rotation shaft 7a, so that each chuck claw 7 is rotatable around a horizontal axis. The back of each chuck claw 7 is formed into a bent back and disposed so as to make its bent back contact to the chuck-moving member 4. When the chuck-moving member 4 is pushed downward by the operating piece 6 (moved by a not-shown pickup moving mechanism), each chuck claw rotates, due to its self-weight, around its rotation shaft 7a in a direction F shown in FIGS. 9 and 10.
As a result, a tip portion of each chuck claw 7 is made to retract and submerge into a predetermined inside spacing (refer to the unclamped state shown in FIG. 9). In contrast, when the pushing force that has been given to the chuck-moving member 4 from the operating piece 6 is removed, the spring 5 allows the chuck-moving member 4 to move upward. Thus the chuck-moving member 4 pushes each chuck claw 7 upward, so that each chuck claws 7 is forcibly rotated around its rotation shift 7a in a direction E shown in the figures. By this rotation, the tip end of each chuck claw 7 protrudes upward from the inside spacing beyond a disc-mounting surface of the disc table 2, so that the chuck claws 7 are able to clamp the disc 8 (refer to the clamped state shown in FIG. 10). Each chuck claw 7 has a stopper 7b formed on both sides thereof and the stopper 7b regulates the rotation of each chuck claw 7 in the direction E by making it contact a given portion of the disc table 2.
As described above, in the conventional clamp mechanism, rotation of the plural chucks 7 in the predetermined clamping direction allows the disc 8 placed on the disk table 2 to be clamped. When removing the disc 8 from the disc table 2, the chucks 7 are made to rotate in the unclamping direction due to the self-weight.
Thus, the clamping and unclamping operations are realized in such that the chucks 7 rotate upward to emerge above the disc 8 placed on the disc table 2 or rotates downward below the disc 8. It is therefore unnecessary to arrange a rotational mechanism to press the disc 8 downward from the top thereof.
There has been known a conventional information replay apparatus capable of replaying information in an attitude oblique to the ground. In this case, an information-recording surface of a disc contained in the apparatus is also positioned in an oblique angle to the ground.
However, the conventional information replay mechanism comprising the foregoing clamp mechanism has a problem that the chuck claws 7 remain protruded over the disc 8 on the disc table 2, without being rotated downward below the turntable. To be specific, this problem may happen in cases where the disc 8 (that is, its information recording surface) is positioned in a perpendicular attitude or in oblique attitudes closer to the perpendicular angel to the ground. This is because the self-weight of each chuck claw 7 is utilized to rotate in the unclamping direction.
If such a situation is caused, it is no longer difficult to smoothly unclamp the disc 8. In addition, it is also difficult to load the disc 8 on the disc table 2, provided the chuck claws 7 protrudes upward. That is, the chuck claws 7 that have protruded to emerge from the disc table 2 become obstacles to the disc 8 to be loaded newly.
In addition to the foregoing problem, there is another problem that the shape of each chuck claw 7 is restricted in design. In other words, there is the necessity of considering the gravity center of each chuck claw 7. This problem is also attributable for the fact that the unclamping operation is based on the self-weight of each chuck claw 7.